Caffeine is a stimulant and too much of it can jangle your nerves and keep you awake, however for pregnant women it can have a far more serious impact. Caffeine, whether from coffee, chocolate or sot drinks like colas, has been linked to a higher risk of miscarriage reported this week by the American Journal of Obstetrics & Gynaecology.

Even a small amount of caffeine can increase the risk, but if the daily intake is the equivalent of at least two cups of coffee or five cans of a soft drink with caffeine, then women in the study were twice as likely to miscarry as women who never, or rarely, had any caffeine in their diet. Women who suffer a lot of nausea in pregnancy, and had a high caffeine intake, had an even higher risk of miscarriage.

The study was based on 1,063 pregnant women living in the San Francisco area and confirmed previous studies about the increased risk of caffeine intake and miscarriage. These studies found that caffeine crosses the placenta but is poorly metabolised by the foetus and may influence cell development and decrease placental blood flow.

To put it into perspective, the risk factor is substantially elevated if you have over 200mg a day from all sources and a large mug of 150 mill of coffee contains 100 mg of caffeine.

However, as I have previously mentioned in this article about caffeine, caffeine-free doesn’t quite mean what it says. It depends on a number of factors such as what process of decaffeinating is used and what different manufacturers product requirements and standards are.

Remember that there is approximately 2mg caffeine in decaf coffee and hot chocolate and if tea drinkers are not immune either as there is approximately 39 mg of caffeine in the average mug of tea.